To treat rhythm problems of a patient, and especially auricular fibrillation, it is known to initiate a procedure of cardioversion by electric shock. Such a cardioversion can lead to cerebral vascular events or to peripheral embolisms by detachment of part or all of a preexisting thrombus at the level of the left auricle. Thus, transesophageal echography is therefore generally performed prior to cardioversion in order to correctly visualize the left auricle and thus to detect the possible presence of a thrombus. A known probe for such a transesophageal echography generally comprises an ultrasonic sensor at the distal end of an endoscope.
One method of cardioversion in current use consists in producing electric shocks internally or by endocavitary means. Such a method constitutes an invasive procedure that is very difficult to implement. Another method consists in producing electric shocks externally by applying two electrodes to the patient's chest. This method is relatively easy to implement but requires general anesthesia.
Another method of cardioversion consists in producing electric shocks esophageally using an endoscope provided with several electrodes on its distal portion. This procedure requires simple sedation, but can produce complications when it follows prior transesophageal echography. Actually, in practice, the technician sometimes experiences problems in reinserting a new probe into the mouth of the patient where it can roll up because there is a risk of rejection of the probe by the patient due to the fact that the esophageal tissues are already irritated, to say nothing of the risks of lesion or perforation of the esophagus due to repeated insertions of endoscopes. To prevent such complications, the applicant suggested, in Application WO 98/18519, an endoscope equipped with an ultrasonic sensor and at least one electrode on its distal end that makes it possible to carry out both echography and transesophageal cardioversion during the same procedure, either simultaneously or in succession without the necessity of repeated insertion and removal of the probes through the esophagus. By using one electrode on the articulated portion of the endoscope near the ultrasonic sensor, such an endoscope, moreover, allows the technician to exactly visualize the location at which he wants to perform the cardioversion and to ensure close approach of the electrode to the wall of the heart, thus leading to especially effective cardioversion.
Moreover, for reasons of hygiene and public health safety, it is preferable to protect the distal ends of the endoscopes that are inserted into the esophagus for each procedure by means of a disposable latex or polyurethane protective cover. The use of such a protective cover proves incompatible with the presence of electrodes integrated on the distal end of an endoscope, because the electrical power released locally by the electrodes can melt or burn the thin wall of the cover. One possible solution that could be envisioned would consist in providing a cover that is made of a material with sufficient thermal resistance and thickness to resist the electrical power released by the electrodes. This solution, however, would entail a prohibitive cost, given the one-time use of the protective cover.
Consequently, in order to proceed under more certain conditions of hygiene and safety, physicians currently prefer to use cardioversion with electric shocks externally, in spite of its disadvantages.